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Alternative Materials for Landfill Liners and Covers
IGC 2009, Guntur, INDIA
ALTERNATIVE MATERIALS FOR LANDFILL LINERS AND COVERS
M.R. Patil
Asst. Prof, Department of Civil Engg, BVBCET , Hubli–580 031, India.
E-mail: [email protected]
S.S. Quadri
Professor, Department of Civil Engg., BVBCET, Hubli–580 031, India.
E-mail: [email protected]
Lakshmikantha H.
Environmental Officer, Karnataka State Pollution Control Board, Bangalore–560 001, India.
E-mail: [email protected]
ABSTRACT: An engineered landfill is a facility designed for the safe disposal of solid wastes. The bottom liner and a top
cover, of the landfill are considered as the most critical components. These components are typically composite layers, made
up of geomembrane overlying a compacted clay liner. Similarly landfill cover also consists of compacted clay layer to
prevent the entry of surface water into the landfill. The main factor affecting the quality of compacted clay liners/covers is its
permeability which should not be greater than 1.0 × 10 –9 m/sec. Due to non-availability of suitable soil, it is necessary to
develop alternative material for liners and covers. In the present study Kolar soil and Granite polish wastes are used as basic
materials. The properties of these materials are altered by adding sodium bentonite to achieve the required properties of a
competent material for landfill liners and covers. Also, the performance of these materials is tested under different physicochemical environments. The results of the study show that addition of sodium bentonite brings the permeability to the
required range to use as an alternative material for landfill liners and covers.
1. INTRODUCTION
Solid wastes are the by products of human activities. Due to
increase in population, change in life style, urbanization,
advent of technology and industrialization, there has been
radical change in quantity as well as quality of the solid
waste produced. These wastes have become more hazardous
to human being and environment and demands careful
disposal practices.
Historically, landfill has been the most common practical
method for disposal of solid wastes. Hence an engineered
landfill is a facility designed for the safe and environmental
friendly disposal of solid waste instead of open, unengineered dumps.
Engineering landfill basically consists of bottom liner and a
top cover. These components play very important role in
reducing the leachate quantity and minimizing the ground
water pollution. Hence these are considered as the most
critical components of an engineered landfill facility. Bottom
liner and top covers are composite layers made up of
geomembrane overlying a compacted clay liner of hydraulic
conductivity not greater than 1.0 × 10–9 m/sec. These
composite layers woks as a hydraulic barrier layer in liner
and cover system.
In recent years, geomembrane and geosynthetic clay liners
have been used to replace compacted clay liners. But these
liners are vulnerable to accidental puncture and create a
potential problem with interface shear between their surfaces.
Hence composite clay liners are preferred.
The liners/covers of engineered landfill are multilayered
systems consisting of hydraulic barrier layer as an important
component. The function of this layer is to minimize
percolation of water through the cover system by directly
blocking water and by indirectly promoting drainage or
storage of water in the overlying layers. Furthermore,
hydraulic barrier layer prevents landfill gasses from escaping
into the atmosphere. Such gases are shown to be major
sources of air pollution and ozone depletion. Also this layer
prevents the percolation of leachate into the ground and
reduces underground water pollution.
The hydraulic barrier layer for municipal solid waste landfills
has consisted typically of a composite layer made up of a
geomembrane overlying a compacted clay layer having a
hydraulic conductivity not greater than 1.0 × 10−9m/sec.
(Danial, 1993). Compacted clay layers are of low cost, large
leachate attenuation capacity and resistance to damage. Due
to non-availability of suitable soil at a site/to prevent the use
of fertile soil for these layers, it is sometimes necessary to
blend imported clay materials with local non-productive soils
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and industrial process wastes to achieve a suitable blended
material. The most common blend is a combination of on site
material/industrial process waste with sodium bentonite
which can lower hydraulic conductivity as much as several
orders of magnitude. Compacted clay layers of liners and
covers are of low cost, large leachate attenuation capacity
and resistance to damage. But strong acids and bases can
dissolve the solid materials in the soil, form channels and
increase the hydraulic conductivity. Hence lechate/pore fluid
with pH < 3 or >11 are usually of the most concern.
Table 1: Geotechnical Properties of Study Materials
S.
No
Datta et al. (1999) studied the influence of additives on
compaction characteristics and permeability. To achieve the
low permeability in alluvial soils are blended with fly ash
and clay.
Tiwari & Srivastava et al. (2000) studied the influence of
additives such as fly ash and sodium bentonite and reported
that the compression index (Cc) increases with increase in fly
ash and bentonite and substantial decrease in permeability
with both fly ash and bentonite additives.
3. EXPERIMENTAL PROGRAMME
Granite polish waste is the waste slurry, coming out from the
polishing process of natural granite slabs, to give them fine
finish. As many industries are in operation in the granite
available area throughout the world, considerably large
quantity of this waste is being generated and creating heaps
of this waste which faces disposal problem. Ilakal town in
Bagalkot district is one such place which faces such problem.
Similarly a natural soil from Kolar district which is a nonfertile soil and has limited usage for many other works is
identified for the study. Hence in the present study granite
polish waste from Ilkal in Bagalkot District and natural soil
called Kolar soil from Kolar district of Karnataka State,
India, are used as basic materials for landfill liner and cover.
The geotechnical properties of these soils are determined and
reported in Table 1.
Ilakl granite polish waste and Kolar soil are individually
mixed with different percentages of sodium bentonite and
their change in the permeability is observed with distilled
water. Also the effect of pH on the hydraulic conductivity of
these materials is studied.
Ilkal granite
polish waste
0.42
Natural
Content
Moisture
3.50
2.
Atterberg Limits
Liquid Limit (%)
Plastic Limit (%)
Shrinkage Limit (%)
Plasticity Index (%)
28.30
20.06
9.69
8.24
Non-plastic
Non-plastic
32.08
Non-plastic
Grain size Analysis
Gravel (%)
Sand (%)
Silt (%)
Clay (%)
0.90
54.40
43.20
1.50
Nil
1.00
93.00
6.00
3.
Sivapullaiah et. al. (2003) studied the geotechnical properties
of stabilized Indian red earth and reported that red earth
blended with bentonite, stabilized with lime can be used as
liner material.
Kolar soil
1.
2. LITERATURE REVIEW
Blending of imported clay material with a local soil/
industrial process waste to reduce the permeability is a
popular practice in the construction of landfills. Many
researchers have worked on this approach and following are
few studies.
Properties
4.
Specific Gravity
2.58
2.5
5.
(a) OMC (%)
(b) MDD (g/cc)
16.20
1.71
26
1.46
6.
2.68 × 10–8
Permeability
(m/sec)
2.26 × 10– 8
4. RESULTS AND DISCUSSIONS
4.1 Kolar Soil and Effect of Sodium Bentonite
The properties of Kolar soil show that, it belongs to clayey
sands soil with permeability 2.68 × 10–8 m/sec. Addition of
sodium bentonite shows that, there is a decrease in
permeability as the percentage of sodium bentonite increases.
However the decrease in permeability is marginal even with
addition of 10% of sodium bentonite. The results of the tests
are shown in Table 2.
Table 2: Kolar Soil and Effect of Sodium Bentonite
Property
Kolar
soil
Coeff. of
permeability
(m/sec)
2.68
×
10–8
1%
2.31
×
10–8
Kolar soil +
% Sodium bentonite
3%
5%
7%
1.55 1.32 1.00
×
×
×
10–8 10–8 10–8
10%
0.9
×
10– 9
4.2 Ilkal Granite Polish Waste and Effect of Sodium
Bentonite
The properties of Ilkal granite polish waste show that, it
belongs to silty soil having its permeability 2.26 × 10–8.
Similar to the Kolar soil, there is a decrease in permeability
as the percentage of sodium bentonite increases and addition
of 4% bentonite decreases the permeability of the soil as per
the desired limit. The results of the tests are shown in
Table 3.
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Table 3: Ilkal Granite Polish Waste and Effect of Sodium
Bentonite
Property
Coeff. of
permeability
(m/sec)
5. CONCLUSIONS
To safeguard ground water effectively and economically; the
landfill liner and cover should be made with locally available
materials, which can attain low permeability and high
strength by addition of some additives.
Ilkal granite Ilkal granite polish waste +
polish waste % Sodium bentonite added
1%
2%
3%
4%
2.26
1.80 2.012 1.07
4.98
× 10–8
× 10–6 × 10–9 × 10–9 × 10–10
Following are the major conclusions drawn from the present
investigations.

4.3 Effect of pH on Kolar Soil and Sodium Bentonite
Additive

To study the performance of Kolar soil-sodium bentonite
mixture, leachate as a pore fluid, the permeability of this
mixture is tested under different physico-chemical
environments. It is found that, permeability of the mixture is
increased under acidic and alkaline environments. However
substantial change is observed in alkaline environment. It is
observed that addition of 4% bentonite will reduce the
permeability well within the desirable limit. The results of
the test are shown in Table 4.


Table 4: Effect of pH Kolar Soil and Sodium Bentonite
Mixture
Material
Kolar soil + 10%
Sodium bentonite
Kolar soil + 12%
Sodium bentonite
Kolar soil +14%
Sodium bentonite
Coeff. of permeability
In neutral In acidic
In alkaline
condition environment environnent
m/sec
m/sec
m/sec
–9
–9
0.9 × 10
1.45 × 10
1.72 × 10–9
–
1.05 × 10–9
1.15 × 10–9
–
0.85 × 10–9
1.00 × 10–9
REFERENCES
4.4 Effect of Different Physicochemical Environment on
Ilkal Granite Polish Waste and Sodium Bentonite
Additive
It is found that, addition of 4% sodium bentonite will reduce
the permeability even under alkaline condition. The test
results of the study are shown in Table 5.
Table 5: Effect of Physico-chemical Environments on
Permeability of Ilkal Granite Polish Waste and Sodium
Bentonite Mixture
Material
Ilkal granite
polish waste
+ 4% sodium
bentonite
Coeff. of
Coeff. of
Coeff. of
permeability permeability permeability
in neutral
in acidic
in alkaline
condition environment environment
in m/sec
in m/sec
in m/sec
4.98 × 10–10
9.06 × 10–10
Granite polish waste is fine grained non-plastic, light,
weight material with low permeability
Kolar soil is clayey sands with medium weight material
having low permeability.
It has been observed that the permeability of these
materials decreases with increase in sodium bentonite.
Ilkal granite polish waste with 4% sodium bentonite
added and Kolar soil with 10% of sodium bentonite will
reduce the permeability of these soils to the desired
value to use as a material for landfill liner and cover
when water (pH = 7) is used as a pore fluid.
It has been observed that permeability changes with
change in pH value. It is found that increase in
permeability is high in alkaline medium for both the
study materials. But increase in the permeability of Ilkal
granite polish waste is marginal. It is due to inertness of
the material to the change in pH. However the increase
in the permeability of Kolar soil is slightly more this
may be due to change in structure Recommended
quantity of sodium bentonite to be added to Ilkal granite
polish waste is 4% and that for Kolar soil is 14% to use
them as a competent material for landfill liner and cover.
Daniel David E. (1993). Geotechnical Practices for Waste
Disposal, St. Edumundsdury Press Durystedmundds.
Dutta M., Parida B., Guha B. and Shreekrishnan T.K. (1999).
“Industrial Solid Waste Management and Land Filling
Practice”, Narosa Publishers, Delhi.
Manual on Municipal Solid Waste Management (first
edition), (2002). Govt. of India, Ministry of Urban
Development.
Sivapullaiah and Lakshmikantha H., et al. (2003).
“Geotechnical Properties of Stabilized Indian Red Earth”,
Jr. of Geotechnical & Geological Engineering, 399–415.
Tiwari R.P. and Srivastava et al. (2000). “Utilization of
Industrial Waste (Fly ash) in Landfill Barrier”, IGC-2000,
IIT Bombay, Mumbai: 207–210.
9.18 × 10–10
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